This individual is a most unusual pale colour form, but the indentation between the two anteriormost preformed sheer zones, which characterise this species, is easily visible immediately behind the rhinophores.

This species is incredibly variable in terms of coloration, but all individuals have the 3 “shear zones” on the mantle. I cannot make out if these shear zones are present on this individual and, furthermore, it is unusual in having raised pustules, so it might be an undescribed species.

Berthella martensi comes in a range of colours, but this one is typical, but they can be almost colourless with brown spots. They can also lose parts of their mantle when threatened, so the result is some very odd looking sea slugs.